Experimental studies of self-starting passive mode locking Er3+ -doped fiber ring soliton laser

The mechanism of femtosecond optical pulse generation in a self-starting Er³⁺-doped fiber ring soliton laser and experimental research results are discussed. Using the nonlinear polarization rotation effect of the fiber for sat-urable absorbers (and then self-amplitude modulation) which acts as the mode locking mechanism in an Er³⁺-doped fiber ring cavity laser, stable self-starting mode locking pulses have been generated. The shortest output pulse is 269 fs, with the central wavelength of 1,531 pm at the repetition rate of 21.37 MHz. The average output powen of the two terminators of the laser are 0.25 mW and 0.08 mW respectively. The threshold pump power which sustains the mode locking is 15 mW. Under high pump power, the laser works in a high order harmonic mode locking state. The mode locking pulse durations vs different cavity lengths are also studied. Project supported by Major Project of Chines: Academy of Sciences (No. KJ952-J1-705).     

菌紫质薄膜光致折射率变化的理论计算和实验测量

基因改性细菌视紫红质BR-D96N由于M态寿命的延长而具有显著的光致变色特性.根据Kramers-Kronig变换关系,样品吸收光谱的变化会引起样品折射率的变化.本文首先从实验上测量了BR-D96N薄膜样品在光激发前后的吸收光谱,然后根据Kramers-Kronig变换关系,理论计算了对应此光致变色光谱变化的光致折射率变化光谱.实验上为了直接测量样品的光致折射率变化,采用Michelson干涉方法测量BR-D96N薄膜在不同探测波长下的光致折射率变化量,并与理论计算曲线进行了比较.     

Aerobic Alcohol Ammoxidation Catalyzed by Copper(I)/Amino Acid: a Scalable Protocol to Nitriles

A facile, practical and scalable catalyst system for alcohols ammoxidation into nitriles was developed using amino acid as ligand, oxygen as terminal oxidant and copper iodide(CuI) as catalyst. The catalyst system shows excellent functional groups compatibility for a wide range of testing substrates, even the substrates bearing oxidation- sensitive groups such as MeS-, alkenyl and -NH₂ can also work well. In addition, the protocol is readily scaled up to more than 20 g and the product can be obtained just through filtration or distillation without conventional column chromatography.     

Spectroscopic characteristics of Yb3+-doped Li3Ba2Y3(WO4)8 crystal

This paper reports the spectroscopic properties of Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal. The polarized spectral properties of Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal were investigated. The laser performance parameters β_min, I_sat and I_min of Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystals have been also established. Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal has a broad FWHM of the gain cross-section and larger absorption and emission cross-sections. These results may regard the Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal as a tunable laser material.     

Experimental studies of high order soliton compression effect and gain characteristics in femtosecond laser pulses E3+r-doped fiber amplifier

Seed laser pulses with average power of 146 μW and pulse duration of 480 fs were amplified to 14.5 mW. The pulse duration was compressed to 260 fs using 6 m high concentration E3+r-doped fiber under forward pumping. The amplified signal pulse energy was 0.691 nJ (corresponding to a peak power of 2 657.7 W) and the repetition rate was 20.84 MHz. Spectrum breakup was observed simultaneously. The spectrum of pulses amplified by 3 m E3+r-doped fiber remains a single peak under different pump power. The amplified pulse duration was compressed abnormally with the increasing pump power using the backward pumping; that is, the amplified pulses were compressed with the increasing pump power under low pump power. When the pump power reached 38 mW, the shortest amplified pulse duration was 309 fs. With further increase in pump power, the amplified pulses began broadening, accompanied by a single peak spectrum under different pump power.     

Effects of guanidinium cations on structural,optoelectronic and photovoltaic properties of perovskites

Guanidinium (GA) cations are intentionally introduced in MAPbl3 perovskite by considering its potential capability of stabilizing the material through plenty of...     

利用菌紫质薄膜进行角度复用和偏振复用全息存储实验研究

全息光存储以其高密度、大容量、高速并行数据存取而成为光存储领域的一个重要研究方向。生物光致变色材料———菌紫质是一种新型可擦重写全息记录介质。实验证明了使用菌紫质薄膜进行角度复用和偏振复用全息存储的可行性。利用菌紫质的光致变色特性,采用90°角度复用全息存储光路,在BR-D96N薄膜样品同一位置上实现了6幅全息图存储,并分别读出了无串扰的再现像。利用菌紫质薄膜的光致各向异性进行了偏振复用全息存储,在BR-D96N薄膜样品的同一位置上存储了两幅正交偏振光记录的图像,用原参考光再现和偏振片选择,可分别读出这两幅图像。